Fluid dispensing apparatus



Oct. 2, 1956 K. w. REYNOLDS r-rrlu. 2,764,992

FLUID DISPENSING APPARATUS 2 SheetS-Sheet 1 Original Filed July 16, 1952 Comp/255550 .99 4/2 Compeasssa A/P lnven t'ovs: Kenne th W. Rel no Lds, John' A. BiLLson, CLi F FT'OT'd E. Rausch, by Their" A t vne Oc't. 2,1956 K. w. REYNOLDS EI'AL 9 FLUID DISPENSING APPARATUS Original Filed July 16, 1952 2 Sheets-Sheet 2 Invervtovs: Kenne th W. Re noLds, 58 /37 John ABiLLson,

/36 CLi F Fovd E. Rausch,

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United States Patent 9 2,764,992 FLUID DISPENSING APPARATUS Kenneth W. Reynolds and John A. Billson, Willoughby, and Clifiord E. Rausch, Warren, Ohio, assignors to General Electric Company, a corporation of New York Original application July 16, 1952, Serial No. 299,286, now Patent No. 2,732,847, dated January 31, 1956. Divided and this application April 12, 1955*, Serial No. 500,952

3 Claims. (Cl. 134-167) Our invention relates to apparatus for delivering a liquid substance into the bottom region of a hollow receptacle and removing it therefrom, and is especially useful for removing a metallic reflector coating from selected areas of the inner walls of electric lamp bulbs, in particular, from the bowl ends thereof. The present application is a division of our copending application Serial No. 299,286, filed July 16, 1952, now Patent No. 2,732,847, dated January 31, 1956.

In the production of glass lamp bulbs having a metallic reflecting coating on certain selected areas of their inner walls, the common practice is to first coat substantially the entire inner surface of the bulb either by depositing metallic silver or other like metallic reflective coating material from a solution, or by thermally vaporizing the coating metal onto the bulb wall while the latter is in a partially evacuated condition. Subsequently, the metallic coating is removed from that area of the bulb inner wall which is to be left clear. Thus, in the production of a metallic reflector coated bulb intended for direct lighting purposes, the metallic coating is removed from the rounded or bowl end portion of the bulb up to substantially the line of maximum diameter thereof. In this operation it is highly desirable that the metallic coating have a sharp, clean cut-ofi line, and further that this cut-01f line be accurately and uniformly located in the bulbs in accordance with the optical eflect which is desired. It is also of great importance that the coating removal operation be carried out in a way such as not to damage or impair the retained reflector coating in any way.

The procedure most generally employed at present for removing the metallic coating from the bowl end of an interiorly coated lamp bulb consists in chemically dissolving the metallic coating oif such bulb wall portion by carefully filling the coated bulb, while held in an upright neck-up position, to the desired cut-ofi level with a suitable solvent or acid dissolving solution and, after permitting the solvent or acid to remain in the bulb for the required length of time to dissolve the metal of the coating up to the desired cut-off line, then removing the dissolving solution from the bulb. It is extremely important that the solvent charges be introduced into the bulb without any splashing and in a condition substantially devoid of air bubbles since otherwise objectionable pinholes would be formed in the retained reflector coating due to the spattering thereonto of particles of solvent resulting either from the aforementioned splashing thereof or from the bursting of the air bubbles after rising to the surface of the solvent in the bulb. Likewise, after the withdrawal of the measured charge of dissolving solution from the bulb, it is imperative that no drops of the withdrawn solution be allowed to fall back into the bulb where they would spatter onto the portion of the refiector coating to be retained and thus also form objectionable pinholes therein. In addition, in carrying out such a dissolving process, care must be taken to avoid the possibility of drops of solvent running down the side walls of the bulbs over the portions of the coating to be retained with resultant impairment thereof.

g ,It is anobjectof our invention, therefore, to provide Patented Oct. 2, 1956 'ice - effectively meets all of the above mentioned performance requirements.

A further object of our invention is to provide apparatus for removing an internal metallic coating from the bowl end portion of a lamp bulb or similar hollow glass article by introducing a dissolving solution into and withdrawing it from the bulb and which does not require the use of any exhausting equipment for effecting the withdrawal of the dissolving solution from the bulb.

Further objects and advantages of our invention will appear from the following detailed description of species thereof and from the accompanying drawings.

In the drawings,

Fig. 1 is a somewhat diagrammatic illustration of a dissolving mechanism including a filling head in accordance with our invention;

Fig. 2 is a vertical section of a solvent charge-measuring flask;

Fig. 3 is a top view of the filling head;

Figs. 4 and 5 are vertical sections, taken on the lines 44 and 55, respectively, of Fig. 3;

Fig. 6 is a fragmentary elevation, partly in section, of a modified form of filling head; and

Fig. 7 is a fragmentary vertical section of the filling head illustrated in Figs. 4 and 5.

Referring to the drawings, a glass eleectric lamp bulb 19, having a metallic reflecting coating 20 on substantially its entire interior surface is supported in a holder 7 which is mounted for vertical reciprocation to bring a filling head 62 into the interior of the bulb for removal of the coating 20 from the lower bowl end of the bulb. The holder 7 may be in the form of a tray for supporting a number of bulbs and may be actuated by mechanism such as that fully described in the aforesaid copending application.

Referring to Figs. 4 and 5, the filling head 62 comprises a vertically disposed outer or main support tube 91 which is fastened at its upper end to a support bracket 88 for the filling head and is closed off in an airtight manner at its upper and lower ends by closure plugs 92 and 93, respectively. The tube 91 is provided adjacent its upper end with a connecting nipple 94 for connecting the interior of the tube to a supply of compressed air through a length of chemically resistant tubing 95 (Fig. 1) and a pipe 97. The supply of compressed air to the filling head tube 91 is controlled by a suitable valve 97 (Fig. 1) in the compressed air supply line 97.

At its lower end the tube 91 is provided with an aperture 98 (Fig. 4) for egress of compressed air from the tube, as well as a surrounding sleeve 99 of yieldable material such as rubber which covers the aperture 98 in the tube and is either stretched tight over, or tightly clamped around the tube, at regions to either side (i. e., above and below) of the aperture 98, so as to have an airtight grip on the tube at the said regions for entrapping the compressed air passing out of the tube 91 through the said aperture. As shown in Fig. 7, the airtight grip of the sleeve 99 on the tube 91 may be obtained by clamping the sleeve around the tube by means of binding wires 100.

In the normal operation of the apparatus, the rubber sleeve 99 is located within the substantially straight neck portion 101 of the bulb 19 when the latter is raised to its elevated position to effect the introduction of the filling head 62 into the bulb. When compressed air is subsequently supplied at the proper pressure to the interior of the tube 91 through the connecting tube 95 and nipple connection 94, it passes out through the aperture 98 in the tube and expands .or inflates the portionof the sleeve 99 opposite the aperture against the inside wall of the surrounding bulb neck 101, as indicated at 102 in Fig. 7, so as to form an airtight seal with the bulb neck whereby the interior of the bulb is closed off from the atmosphere. To prevent excessive inflation of the rubber sleeve 99 in a direction out the open end of the bulb such as might resuit in the bursting and destruction of the sleeve, a floating protective collar or sleeve 103 is provided on the tube 91 for blocking off the space between the bulb neck 101 and the upper end portion of the rubber sleeve 99, the collar 103 being freely slidable on the tube and having its inner wall recessed or undercut a suflicient distance inwardly from its lower end, as indicated at 104, to provide a space for accommodating substantially the entire length of the rubber sleeve 99 therein. The collar 193 is of smaller outside diameter than the neck opening 1115 of the bulb 19 so as to be insertable thereinto, and its lower end is externally bevelled or tapered, as indicated at 196, for engagement with the outwardly flaring portion 197 of the bulb neck, during the upward movement of the bulb over the filling head 62. In its normal inoperative position as shown in Figs. 4 and 5, the collar 193 is sup ported in place on the tube 91, in a lower position wherein it extends down over and encloses substantially the entire length of the rubber sleeve 99, by a spring snap ring 108 which is locked in an external annular groove 109 in the tube 91 and engages with the internal shoulder 110 on the collar 103 to support the latter. When a bulb 19 is raised up over the filling head 62, the flaring neck portion 107 of the bulb engages the tapered lower end 166 of the collar 193 and lifts the latter along therewith. By virtue of its engagement with the flaring bulb neck portion 107, the lower end of the collar 103 thus not only acts to block off the space between the bulb neck and the rubber sleeve 99 toward the open end of the bulb neck so as to prevent excessive dilation and possible blow-out of the rubber sleeve during the subsequent sleeve-expanding operation, but it also acts to center or vertically align the bulb 19 relative to the filling head 62 in order to assure the production of a straight (i.e., non-tilted) cut-elf line during the subsequent reflector coating removal operation.

Extending vertically through the filling head outer tube 91 and its end closure members 92, 93 in an airtight manner is a small inner tube 111 having one or more outlet openings 112 (Fig. in its projecting lower end 113. The projecting upper end of the tube 111 is connected by a length of chemically resistant tubing 114 (Fig. l) to the compressed air supply. The tube 114 is connected to the compressed air supply line 97 for the rubber sleeve 99 of the filling head, the supply of air to the tube 114 being independently controlled by a valve 117 in the said air line 97.

The outer tube 91 is also provided with two additional inner tubes, i.e., an inlet tube 118 for the acid solvent and an outlet tube 119 therefor, which tubes extend vertically through the outer tube and its end closure members 92 and 93 in an airtight manner. Attached to the lower ends of the tubes 118, 119 is a combination drip and bubble trap device 1219 from which the acid solvent is released into the bulb 19 and withdrawn therefrom. The particular trap device 120 shown in Figs. 4 and 5 comprises a drip trap unit 121 and a bubble trap unit 122 arranged one above the other and respectively adapted to prevent the dripping into the bulb 19 of any drops of acid solvent collecting within the inlet or outlet tubes 118, 119 either before or after the actual introduction of the acid solvent charge into the bulb and to prevent the passage into the bulb of any bubblesin the acid solvent charge which might thereafter burst within the bulb or float against the reflector coated inner side wall of the bulb with resultant production of either pinholes in the portion of the reflector coating to be retained or in irregularities in the cut-off line thereof.

The drip trap unit 120 comprises a vertically extending tubular outer shell 123 closed at its upper end by an upper plug or stopper member 124 which is snugly fitted within the shell and attached to the lower ends of the inlet and outlet tubes 118, 119, the plug 124 being provided for such purpose with vertically extending tube-receiving bores 125 and 126 into which the respective tubes 118, 119 snugly fit and are securely fastened. The other side of the plug 124 is provided with a hollow 127 which communicates with both the bores 125 and 126 to thereby provide a common interconnecting chamber therefor. Snugly fitted within the lower end of the shell 123 is a lower stopper plug or trap member 128 having an upright U-shaped channelway 129 in its cylindrical side surface which, in conjunction with the closely surrounding shell 123, forms a conventional sink-type U-trap passageway. The U-passageway 129 communicates at one of its upper ends with the chamber 127 and at its other upper end with a cross passageway 130 which, in turn, connects with a centrally located vertical bore 131 in the plug member 128, the said bore 131 extending upwardly from the lower end of the plug member and being closed at its upper end.

The bubble trap unit 122 comprises a vertically extending tube 132 which is fastened at its upper end in an airtight manner to the lower end of the plug member 128, as by a screw-threaded connection therebetween, and is closed off at its lower end by a finely perforated bubblecatching filter member 133 such as a stainless steel wire screen, for instance. A nozzle tube 134, fitted within and communicating with the bore 131 in the plug member 128, projects from the lower end of the latter down through the tube 132 to a point a short distance above the screen 133, e.g., a distance of the order of 42 inch or so. The tube 132, which is of relatively large size as compared to the nozzle tube 134, thus provides a bubble dispersion chamber 135 for collecting therein any bubbles that may be filtered by the screen 133 from the acid solvent charge as it flows out the lower end of the nozzle tube 134.

The use of the drip trap 121 is necessary to the satisfactory carrying out of the reflector dissolving operation in those instances where the acid solvent employed for the dissolving operation is of a type which does not possess suflicient surface tension to enable the screen 133 to effectively retain any drops of solvent which would otherwise fall thereonto from the inlet or outlet tubes 118, 119, since such drops of acid solvent would then pass through the screen 133 and drop against the bottom or bowl end 26 of the bulb where they would splatter against the portion of the reflector coating to be retained on the side wall of the bulb and produce pinholes therein. However, where the acid solvent employed is of a type possessing sufficient surface tension to enable the wire screen 133 to retain any drops of acid solvent falling thereonto, the drip trap 121 may be omitted from the trap device 120 and only the bubble trap unit 122 used, as illustrated in the modification shown in Fig. 6.

In this modification the bubble trap tube 132 is fitted at its upper end with a plug 136 which may be screwed into the tube 132 in the same manner as the drip trap plug 128 in Figs. 4 and 5, and is provided with a pair of tube-receiving apertures 137, 138 in which are fitted a pair of stainless steel tubes 139 and 140, respectively.

'Like the nozzle tube 134 in Figs. 4 and 5, the tubes 139,

140 extend down to a point a short distance of the order of A; inch or so above the screen 133 and are connected, at their projecting upper ends, by short lengths of flexible chemically resistant tubing 141, 142 to the lower ends of the inlet and outlet tubes 118 and 119, respectively. The flexible connection tubing 141, 142 imparts a limited amount of lateral flexibility to the lowermost portion (i. e., the bubble trap portion 122) of the filling head, which is of added advantage because it tends to prevent breakage of the bubble trap outer tube 132 (which is preferably made of a synthetic plastic material) in those cases wherethe bulb is overly misaligned with the-filling head so as to strike against the bubble trap tube 132 when the bulb is elevated up around the filling head. If desired, however, the tubes 139, 140 and the flexible connection tubing 141, 142 may be omitted and the tubes 118, 119 instead extended down through the plug 136 and into the bubble trap tube 132.

The projecting upper end of the inlet or fill tube 118 of the filling head 62 is connected, by a flexible chemically resistant length of tubing 143, to the outlet 144 of a charge-measuring device or flask 145 while the outlet or return tube 119 is connected, by a length of similar flexible tubing 146, to a return inlet 147 of a reservoir or tank 148 containing a supply 149 of the acid solvent employed for the reflector-dissolving operation. The tank 148 is mounted on a supporting framework (not shown) alongside and above the level of the filling head 62 and is provided with suitable electrical heating elements 152 (Fig. l) for maintaining the acid solvent supply 149 therein in a heated condition, for example, at a temperature of the order of 110-130 F. The solvent employed for the reflector-dissolving operation may be any material suitable for the purpose and will, of course, depend upon the particular character or composition of the reflector coating which is to be removed. However, where the reflector coating on the bulb 19 is composed of silver, a solvent comprising a mixture of sulphuric acid, chromic acid, and water, preferably in the proportions of the order of 4% sulphuric acid, 1% chromic acid and the remainder water, has been found entirely satisfactory. If desired, a suitable wetting agent may be incorporated in such a solvent material in order to obtain a sharper or cleaner cut-ofl? line for the reflector coating to be retained on the bulb.

The tank 148 is provided with an outlet 153 located below the level of the return inlet 147. The tank outlet 153 is connected, by a length of flexible chemically resistant tubing 154, to a corresponding inlet 155 of the charge-measuring device 145. During the operation of the apparatus, the supply 149 of acid solvent in the tank 148 is maintained at a fixed level therein and is re-circulated through the charge-measuring device 145 into successive bulbs 19 and thence back into the tank 148.

The flow of the acid solvent from the tank 148 into the charge-measuring device 145 by gravity flow, and then to the filling head 62 and associated bulb 19 and finally back into the tank 148, is controlled by three similar pinch clamps 166, 167 and 168 corresponding in number to the fiexible tubes 143, 146 and 154 respectively and by which they are either pinched closed or opened to shut off or permit the flow of the acid solvent therethrough.

The charge-measuring device or flask 145 accurately measures the individual charge of acid solvent for each bulb 19 so that uniform amounts of solvent are introduced into each of the bulbs. The charge-measuring device 145 is supported at an elevation substantially corresponding to that of the tank 148 and above that of the filling head 62. As shown more particularly in Fig. 2, the charge-measuring device 145 comprises a vertically arranged tube or flask 184, preferably made of glass, provided with an outlet connection 144 at its lower end and a side inlet connection 155 located more or less midway between the upper and lower ends of the tube at a level slightly below the corresponding tank outlet 153 to which it is connected by tubing 154. The upper end of the tube or flask 145 is closed ofl by a rubber plug or stopper 185 having a central bore 186 in which a metal tube or bushing 187 is snugly received so as to have an airtight fit therein. The bushing 187 projects outwardly above the top of the stopper 185 and is provided with an enlarged head or collar portion 188 which rests on the top of the stopper 185. The inner and outer walls of the collar portion 188 converge upwardly to a sharp edge to form a circular knife-edged seat 189 at the top of the collar.

Dis'posed within the tube or flask is a float 190, preferably made of glass and consisting of a lower bulb portion 191 having a vertical stern portion 192 extending loosely through the passageway 186 in the bushing 187 and projecting upwardly therebeyond. The stem 192 of the float is provided, internally of the flask 184, with an enlargement or stop collar 193 which is adapted to abut against the lower end of the bushing 187, as the float rises during the filling of the flask 184 with acid solvent from the tank 148, to thereby limit the upward movement of the float and thus avoid any tendency of the float to become wedged or to bind in a tilted position, when elevated, such as would prevent it from moving freely downward in the flask 184 when the fluid is subsequently withdrawn therefrom. The limiting of the upward movement of the float 190 by the stop collar 193 thereon also serves to prevent excessive protrusion of the fragile glass stem 192 outwardly of the flask such as would render it subject to accidental breakage. To avoid the possibility of the stop collar 193 closing or sealing off the passageway 186 in the bushing 187 (during the filling of the flask 184- with acid solvent from the tank 148) such as would result in the building up of a back air pressure in the upper region of the flask above the level of the acid solvent therein, which pressure would therefore interfere with the flask-filling operation and would prevent the filling of the flask with the proper amount of acid solvent, the lower rim end of the bushing 187 may be formed with suitable serrations or notches 194 to provide passageways which communicate with the bore 186 of the bushing, when the float stop collar 193 is abutted against the lower end of the bushing, so as to permit the flask 184 to breathe at such time through the bushing passageway 186.

Snugly fitted on the projecting upper end portion of the float stem 192, so as to have an airtight fit therearound, is a rubber collar 195 which is adapted to move down onto and seat against the circular knife-edged seat 189 of the bushing 187, during the flow of acid solvent out of the flask 184 into the filling head 62, to hermetically close-off the passageway 186 through the bushing and thus stop the outward flow of acid solvent from the flask into the filling head by reason of the partial vacuum created in the upper portion of the flask by the continued slight lowering of the acid solvent therein immediately following the seal-off of the flask by the collar 195. The collar 195 thus acts as an atmospheric pressure valve to accurately control the amount of acid solvent flowing out of the flask 184 into the filling head 62.

The flask 184 rests at its lower end on a suitable support member (not shown) which is vertically adjustable to thereby permit accurate positioning of the flask at the correct elevational position.

The operating cycle of the reflector-dissolving mechanism begins when the bulb support 7 is moved upward to bring the head 62 into the bulb 19. During the upward movement of the bulb support 7, pinch clamp 166 is in a closed position and pinch clamps 167 and 168 are in a. open position so as to permit continued flow of acid solvent by gravity from the tank 148 through tube 154 into the flask 145 to fill the latter, such flow having been initiated previously to the start of upward movement of the support 7, specifically at the start of air blow-out of the acid solvent from a bulb 19 during a preceding reflectordissolving cycle. By the time the support 7 reaches the upper limit of its travel, suflicient time has elapsed for the acid solvent in the flask 145 and in the tank 148 to become equalized at a common level L3 (Fig. l) the flask 145 then being filled with its individual charge of acid solvent for the bulb 19.

When the bulb support 7 has reached its upper limit of travel, the pinch clamps 167 and 168 are closed and, at the same time, the pinch clamp 166 is opened which then allows the acid solvent in the flask 145 to flow out through the tube 143 to the filling head 62 and into the bulb 19. At the instant the pinch clamp valve 166 is opened, a continuous column of acid solvent remaining from the preceding dissolving cycle is present in the tube 143 and extends from the flask 145 through the connecting tube 143 and down to the lower end of the inlet tube 118 of the filling head 62, the said liquid column having been retained within the tube 143 by the vacuum created in the upper portion of the flask 145, above the level of the acid solvent remaining therein, by the closure of the atmospheric pressure valve during the previous dissolving cycle. However, since at the time the valve 166 is opened the column-retaining vacuum in the flask 145 is no longer present therein due to the opening of the atmospheric pressure valve at the top of the flask, atmospheric pressure therefore exists on both ends of the continuous liquid column in the tube 143. As a result, a siphoning action is initiated on the liquid column due to the lower elevation of the filling head 62 relative to the flask 145, the siphoning action thus causing the acid solvent to flow through the tube 143 from the flask 145 to the filling head 62 and into the associated bulb 19. The flow of acid solvent to the filling head 62 then continues until the atmospheric pressure valve is once again closed by the rescaling of the valve collar 195 against the valve seat 189, which is brought about by the lowering of the float 190 in the flask. The closing of the atmospheric pressure valve 195 stops the flow of acid solvent out of the flask 145 through the action of the vacuum which is created in the upper part of the flasks by the continued slight additional outflow of acid solvent therefrom which takes place immediately following the closure of the valve 195, The partial vacuum thus created in the flask 145 then holds the continuous column of acid solvent in the connecting tube 143, extending from the flask 145 into the filling head 62. Uniformly alike amounts or charges of acid solvent are thus measured by the valve 195 and are introduced into successive bulbs 19 by the filling head 62, the amount of the acid solvent charges being so regulated by the elevational setting of the valve 195 on the float stem 192 as to submerge the portion of the internal reflecting coating on the bulb to be removed, i. e., fill the bulb 19 up to the desired reflector cut-01f level thereof which, for example, may be at the maximum diameter of the bulb as shown at 210 in Fig. l.

Following a predetermined time interval sufficient to permit the acid solvent in the bulb 19 to thoroughly dissolve the internal reflector coating off the submerged portions of the bulb walls, for example, 22 seconds or so from the start of upward movement of support 7, the acid solvent in the bulb 19 is removed therefrom by introducing low pressure air into the bulb, while the latter is closed off to the atmosphere at its neck end, to thereby force the solvent out of the bulb back up through the filling head 62 and return tube 145 and back into the reservoir or tank 148. For this purpose, at the end of such timed reflectordissolving interval, the pinch clmp 166 is returned to its closed position and pinch clamps 167 and 168 to their open position, and the valves 97', 117 are opened so as to supply air to the blow-out tube 111 and the rubber sleeve 99 of the filling head 62. The opening of the air valve 97 causes inflation of the rubber sleeve 99 on the filling head 62 (with resultant seal-oft of the bulb from the atmosphere) while the opening of air valve 117 causes introduction of compressed air into the bulb through air tube 111 so as to force the acid solvent out of the bulb back up into the filling head 62 and through the opened return tube 146 back into the tank 148 from which it then flows out through the opened flask-filling tube 154 into the respective flask 145 to refill the latter.

At the expiration of a relatively short predetermined air blow-out time interval (for example, around 5 seconds or so) sufficient to permit substantially all of the acid solvent in the bulb 19 to be forced out therefrom, the air valves 97' and 117 are closed and thus terminate the air blow-out operation. The bulb support 7 is then lowered to complete the cycle.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A filling head for delivering a liquid substance into the bottom region of a hollow article and withdrawing it therefrom, said head comprising a vertically extending support tube closed to the atmosphere at its opposite ends, a rubber sleeve fitted over the lower end portion of said tube and having its opposite end portions fastened tightly around said tube to form an airtight connection whereby the intermediate portion of said sleeve may be inflated, said tube having an aperture in the wall thereof intermediate the said end portions of the rubber sleeve and communicating with the inner side thereof, a conduit connected to the interior of said tube at a point above the said rubber sleeve and connected to a supply of compressed air for inflating said sleeve, a liquid sup ly conduit ex tending through and projecting beyond the lower end of said tube and having an outlet opening at its lower end, and a protective collar on said support tube normally supported thereon in a lowered position closely surrounding said rubber sleeve, said collar being free slideable on said support tube upwardly from its lowered position to thereby expose the said rubber sleeve.

2. A filling head for delivering a liquid substance into the bottom region of a hollow article and withdrawing it therefrom, said head comprising a vertically extending support tube closed to the atmos here at its opposite ends, a rubber sleeve fitted over the lower end portion of said tube and having its opposite end portions fastened tightly around said tube to form an airtight connection whereby the intermediate portion of said sleeve may be inflated, said tube having an aperture in the wall thereof intermediate the said end portions of the rubber sleeve and communicating with the inner side thereof, a conduit connected to the interior of said tube at a point above the said rubber sleeve and connected to a supply of compressed air for inflating said sleeve, a liquid supply conduit extending through and projecting beyond the lower end of said tube and having an outlet opening at its lower end, and a drip trap attached to the projecting lower end portion of said supply conduit, said drip trap comprising a body member having a vertical discharge passageway therein open at its lower end but closed at its upper end and an upright U-shaped passageway connected at its opposite upper ends to the lower end of said supply conduit and to the upper end of said discharge passageway respectively.

3. A filling head for delivering a liquid substance into the bottom region of a hollow article and withdrawing it therefrom, said head comprising a pair of vertically extending parallel inlet and outlet tubes, a drip trap attached to the lower ends of said tubes and comprising a body member provided with a tubular extension projecting downwardly from its lower end and an internal chamber communicating with both said tubes, said body member further having a vertical outlet assageway closed at its upper end and communicating at its lower end with said tubular extension and an upright U-shaped passageway connected at one end to said chamber and at its other end to the upper end of said outlet passageway, and a bubble trap attached to said drip trap and comprising an enclosure around the said tubular extension to provide a chamber therearound, said enclosure having a discharge opening at its lower end, and filter means bridging the said discharge opening but spaced from the lower end of said tubular extension to. trap air bubbles in the liquid passing through the said discharge opening and collect them in said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,912,278 Key May 30, 1933 2,247,432 Birdseye July 1, 1941 2,273,984 Osborn Feb. 24, 1942 2,650,179 Anderson Aug. 25, 1953 

